Differential Plug Incident

We need some expert advice in regards to our recent incidnet at our Lube shop concnering differential plug.

Story: Regular customer of ours had oil change done 11/9/2010. About ten days later, he went on a long distance trip. While on his way, his rear differential seized up. Cause was due to differential plug missing. Lost most of the gear oil and consequently damaged the dfferential. He took it to dealer and repair came out to about $3,600. Car is 2007 Yukon Denali with 80K miles. Customer believes that we may have been the guilty party as we are the last folks to do the oil change.

Our thoughts: According to our service history, we didn't do anything with the differential. We do 19 point check and normally, we if checked for differential, we would either make notation that it was "checked" or that the service is advised. But in this instance, it was left "N/A". Which means that we did NOT check it.

So, from documentation point, there is no argument. But, it is possible for a bottom tech to have checked for differential and top tech forgetting to put check mark on the service record. It's not likely, but it is a theoretical possibility. So, I cannot say with my life on line that we absolutely did NOT touch the plug. But, it's more likely that we really did NOT check the differential. Having said that, what do you think of our situation? Would you take full responsibility for the repair or half way or none at all? Again, from documentation point of view, it is in our favor for sure. But I'm genuimely more concerned about whether we may have really caused this and if so, we certainly need to take some responsibility. But at the same time, if we didn't do it, then we didn't do it. What's your take?

-tom

Does your 19 point service include differential check? If so, then the customer has an argument either way. I our service description we specifically say that we check the differentials and have had techs mark N/A by accident. If your menu looks like ours I can tell you from experience that any court would rule in favor of the customer since you guys were the last one to touch the vehicle.

The down side of paying half is that you are accepting responsibility. We either pay all or nothing in a situation like this. We installed cameras just for reasons like this. Unless you can prove that you didn't touch the plug you will most likely be held responsible.

Good Luck,

Derek

Customer is suggesting that wen split cost half. So we should take the offer?

We have camera too but it's no use as customer brought this issue to us month after and our camera only hold memory for about 2 weeks.

If you feel like your responsible for the damage and the customer offered to split the bill, sure. But if I was the customer in this situation, I sure wouldn't offer to pay half of the bill if I really thought that you guys were responsible. Just my opinion though.

What was the vehicle mileage on your service record and what was the mileage on the repair?

Now, how many miles would a car typicaly go if the plug was left off?

I am gussing this would happen in a few hundred miles if the plug was left out. If the plug was not tightende and worked it's way out then who knows.

If it was a few hundred miles, the customes case is stronger. If it is a thousand miles or more the customers case is weaker.

There is about 700miles gap between the oil change and repair. He was stranded about 400miles away. So, from the time of the oil change, customer drove the vehicle around town for 10 days about 300 miles. Then he was going on a long road trip and differential finally locked up on him after 400 miles mark on his trip. 700 miles in total.

Now, another mechanic friend of mine suggested this: Assuming that we DID leave the plug out, customer would surely have noticed gear oil drops between 10 days and 700 miles. If someone goes that long and doesn't take heed of such oil dropping and it finally goes bad, the responsibility no longer lies with the shop.

I don't know how much truth is in his claim, but I thought I share that with you and see what you thought about that claim. What do you think? Is he decent or just plain absurd?

-tom

>>Now, another mechanic friend of mine suggested this: Assuming that we DID leave the plug out, customer would surely have noticed gear oil drops between 10 days and 700 miles. If someone goes that long and doesn't take heed of such oil dropping and it finally goes bad, the responsibility no longer lies with the shop.<<<

Your friend is wrong. Have not done a differential check in a while but my recollection is that of you are on a flat surface and pull the plug which is about half way up, nothing should come out. It is not filled up when "full" but just to the level of the fill plug. So, when stationary none will leak. That would happen only with the gears spinning and throwing it around. Any residual drips would be nominal and lets face it, no one moves from where they parked and look where the car had been. You only notice it if you usualy park somewhere and then park somewhere else and can see what was at your usual spot.

I would be more interested in how many miles a car might go without the plug before it siezed, but that doesn't address a loose plug whichj may or may not have happened at your shop since how long a looe plug takes to come out has many variables involved.

I think it's pretty safe to say that "loose plug coming out" is far less likely than a mechanic just failing to put the plug back in.

So, we did some test. We took an SUV for a quick spin around our car wash with the plug absent. As you stated, it will NOT leak when it is still or barely moving. But when the gears start to work, it will definitely leave a visible spill all over. We drove about 100 yards and of that 100 yards, about 90 yards is clearly marked with about an inch wide trail of gear oil from start to end with few breaks in btween.

So, we know that gear oil will leak noticeably at least when the fluid is topped off. Now, I don't know if it will continue to leak until all fluid is gone or if it starts to leak less as fluid level gets lower. But from our test, it is clearely evident that you will notice leak.

But does that still prove anything, would be the important question to ask. And I really am not sure if that changes anything. At the end of the day, we may just need to foot the bill.

-tom

You say "it is clearely evident that you will notice leak," but remember this leak comes out behind the vehicle. If the plug was left out by your employee, your customer would have driven away and almost certainly NOT have noticed the leak. Once they got on the road and most of what would have leaked out in normal driving had done so, then it wouldn't have leaked at all anymore. Then when they got on the highway and drove for an extended time, the unlubricated parts would have gotten hot and seized.

I would say you're lucky to have a customer willing to split the bill with you. If the plug was left loose from the service prior to yours, it would be an amazing coincidence that it fell off so soon after your service. Honestly it seems much more likely that your employee left the plug out than someone else left it loose.

We just did this same thing.. Customer comes in and my manager of 10 years does the pit on it. Notices axle seals leaking, pulls the plug and there's no fluid in it. He forgets to put the plug back in while talking to the customer about the seals and working up a quote.(long story short) Customer came back the same day with no plug and heard some whining. We put fluid in it and drove it around, no more noises. All we have to do is put axle seals in and he's going to be happy. In your case, and we've done this in the past, once a customer has someone else fix the vehicle without telling us first. It's now his baby. If your going to come back on us and want us to pay then he should keep you in the loop from the get go. Now that comes to another point, why did they put a brand new rearend in it? Car has 80k miles on it, if you blow up a motor your going to buy him a used motor with about the same mileage not a $6000 brand new one. Also rearends can be rearbuild for far less money.. If you had to gut the rear- say axles bearings, seals your looking about $600-$1000 bucks TOPS. Gears should be fine..

Ok I found out it was 7 days later our guy came back and with the way the rearend is designed(chevy truck, same as your yukon) there's no way it can run completely out of fluid, the plug hole is on the top side so there will always be little bit fluid in it. New seals and bearings(outside only) cost about $75 bucks our cost. So dealer fix would be about $500 on the high side. Also on the invoice says N/A for the rearend being checked. We use that for a front wheel drive car when there isn't a rearend at all. Your basically saying there's not a rearend to check when you have N/A in the place of checked. Also we only pull the diff plug if we see leaks, if no leaks it's going to have fluid in it.

The description on the invoice says "Found axle oil fill plug missing and casued pinion bearing to lock up damaging rear axle housing. Installed used rear axle assembly" Parts $2,904 and Labor $520. Ouch!

-tom

I had the pinion bearing fail in an old Mercury, though it wasn't the fault of anyone. The bearing guide ring failed, then the pinion shaft bent and immediately destroyed the "pumpkin" which could be removed and replaced fairly easily. On a Chevy there is no removable section to replace if that happens, which means the rear axle housing has to be replaced.